Apparatus for installing cardboard wick drain



KEIJI MAEDA 3,300,987

APPARATUS FOR INSTALLING CARDBOARD WICK DRAIN Jan. 31, 1967 2Sheets-Sheet 1 Filed June 22, 1964 KElJl MAEDA Jan. 31, 1967 APPARATUSFOR INSTALLING CARDBOARD WICK DRAIN 2 Sheets-Sheet 2 Filed June 22, 1964FIG.5

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INVENTOR.

United States Patent APPARATUS FOR INSTALLING CARDBOARD WICK DRAIN KeijiMaerla, Tokyo-t0, Japan, assignor to Kabushiki Kaisha Kato Seisakusho,Tokyo-to, Japan, a joint-stock company of Japan Filed June 22, 1964,Ser. No. 376,856 Claims priority, application Japan, Nov. 18, 1963,38/61,982 2 Claims. (Cl. 6163) The present invention relates to anapparatus for driving a cardboard wick in the cardboard-drain processwhich is known as a consolidation process for fine-grained soils.

An object of the present invention is to provide an apparatus fordriving a cardboard Wick in the cardboarddrain process into athixotropic muddy soil (in the condition of paste, slurry, colloid,etc.) of high water content.

The nature, principle, and details of the invention will be bestunderstood by reference to the following description taken inconjunction with the accompanying drawings in which like parts aredesignated by like reference characters, and in which:

FIG. 1 is a diagrammatic view, partly in section and partly inelevation, showing the general arrangement of one example of theapparatus for driving a cardboard wick according to the invention;

FIG. 2 is a framentary view in longitudinal section showing the lower.part of a driving tube according to the invention and suitable for usein the apparatus shown in FIG. 1;

FIG. 3 is an elevational view partly in vertical section, showing onlythe mouth piece of the driving tube;

FIGS. 4 and 5 are cross-sectional views taken along the lines IV-IV andV--V in FIG. 2, respectively;

FIG. 6 is a fragmentary elevational view in longitudinal section showingthe lower part of a drive tube mouth piece in another embodiment of theinvention;

FIG. 7 is a fragmentary longitudinal sectional view of one type ofconventional driving tube;

FIG. 8 is a fragmentary longitudinal sectional view of another type ofconventional driving tube; and

FIG. 9 is a fragmentary longitudinal sectional view of a mouth pieceserving to illustrate the advantages of the present invention.

In order to fully understand and appreciate the nature and utility ofthis invention, the following brief consideration of the prior art isbelieved to be necessary.

In the conventional apparatus for driving a cardboard wick in thecardboard-drain process, a mouth piece 2 capable of opening and closingmovement is pivoted by pin 3 to the lower end of a driving tube 1 (FIG.7). In operation the driving tube 1 is driven into the ground while thebottom part of a cardboard wick 4 inserted into the driving tube 1 isheld by the mouth piece 2 by means of the pressure of soil acting on thelower surface of the mouth piece 2. After the tube 1 has been insertedto a certain depth, the resistance of the soil acting on arm 5projecting laterally from the mouth piece 2 exceeds the pressure actingon the bottom surface of the mouth piece since the lower soil is softerthan the side soil. At this time the mouth piece is opened so that thedriving tube 1 is pulled up while the cardboard wick 4 is driven down atthe same speed as that of the driving tube 1' by means of a cardboardwick feeding device provided on the top of said driving tube 1 with thewick 4 being thus left in the .ground. However, in the case of drivingthe driving tube into muddy soil, the mouth piece 2 does not open whenthe driving tube is pulled out because the pressure of muddy water actsalways on the lower surface of the mouth piece 2, and the resistanceforce on the arm 5 is very small. Therefore, it has been impossible todrive a cardboard wick into the thixotropic muddy soil.

3,3W,987 Patented Jan. 31, 1967 It is a specific object of the presentinvention to overcome the above described difficulty by providing meanswhereby, instead of the use of a mouth piece capable of opening andclosing movement, compressed air is supplied into the cardboard wickinsertion bore to prevent infiltration of muddy water thereinto andthereby eliminate the undesirable result such that the cardboard adheresto the driving tube due to adhesive material of the mud and is withdrawntogether with the driving tube, whereby driving into the thixotropicmuddy soil is made possible.

However, if the compressed air is supplied from above by utilizing acardboard wick insertion bore 6 in the driving tube 1 as shown in FIG.8, the air penetrates the cardboard wick 4 andflows out upward anddownward through the inner longitudinal channels of the cardboard wickdue to the great contact areas of the air with the cardboard wick.Moreover, in using built-up tpe driving tubes (this type of the drivingtube is needed for convenience in transportation and cleaning of thecardboard wick insertion bore), a large quantity of air leaks and,accordingly, the capaicty of the air compressor must be quite large,with the result that this process is quite impractical. In addition, theair pressures on both sides of the cardboard wick will be unbalanced dueto the leakages of air, whereby the cardboard wick will stick to thewall of the cardboard wick insertion bore so that it is impossible tofeed the cardboard wick.

According to the present invention, for the solution of this problem, onthe wall of the cardboard wick insertion bore and in the lower part ofthe driving tube there are arranged pressure reducing members whichlightly contact the cardboard wick and shut off the lower cardboard wickinsertion bore from the upper bore, with the compressed air beingsupplied to the lower cardboard wick insertion bore whereby muddy wateris prevented from entering into the bore.

For a better undersstanding of this invention, reference is made to thefollowing description of some embodiments thereof taken in connectionwith the accompanying drawings.

Referring first to FIGS. 1 through 5, reference numerals 1 and 7designate respectively a driving tube and a mouth piece connected to thelower edge of the driving tube 1. The driving tube 1 consists of twomembers 8, 8 connected to coupling plates 9, 9 by bolts 10, whereby acardboard Wick insertion bore 6 is formed. Reference numeral 11designates a cardboard wick supporting plate fixed to the wall of thecardboard wick insertion bore.

The mouth piece 7 consists of members 12, 12 which are coupled by meansof bolts and nuts 13, with a nozzle 14' being formed by narrowing thespace between a insertion bore 14 and the cardboard wick 4, and isconnected to the lower part of driving tube 1 by bolts 15 on couplingplate 9, 9.

On the part of the bore wall between the insertion bore 14 of the mouthpiece and the insertion bore 6 of the driving tube, there are attached apressure reducing member consisting of a packing 16 of rubber or otherelastic material and a labyrinth packing 16 having a sawtooth-shapedcross section and a high efficiency of pressure reduction againstleakage of air from below such portion. The packing 16' and labyrinthpacking 16 are in light contact with the cardboard wick 4. Consequently,the upper and lower insertion bores 6 and 14 are separated from eachother, and through air pipes 17 and 18 positioned in the driving tube 1and the mouth piece 7 respectively, compressed air is fed into theinsertion bore 14 via an opening 19. The compressed air is fed into theair pipe 17, through a flexible pipe 20 connected to the upper part ofthe driving tube from an air compressor 22 mounted on a driving machine.The flexible pipe 20 is wound on a hose reel 23 placed on a mast (notshown) which supports the driving tube 1 in a manner permitting only itsascent and descent, whereby the flexible pipe is reeled inor outautomatically according to the ascent or descent of the driving tube.

On the top of'the driving tube 1, there is arranged a cardboard wickfeeding device 24 holding the cardboard wick 4 during the driving-downof the driving tube 1 and feeding the cardboard wick 4 downward at thesame speed as that of the driving tube 1 when the tube 1 is raised. Anair guide plate 25 is fixed to the mouth piece.

According to the above-mentioned construction, when the driving tube isdriven into or raised from muddy soil, the compressed air fed into thebore 14 will leak very slightly into the upper insertion bore 6 due tothe pressure reducing members. The leakage of air through the cardboardwick is also reduced due to the narrow surface of the carboard wick 4 incontact with the compressed air, whereby the compressed air in theinsertion bore 14 is exhausted from the nozzle 14' and this preventsinfiltration of muddy water into the insertion bore 14. Consequently,there is absolutely no possibility of the mud clogging the cardboardwick insertion bore and of upward movement of the cardboard wicktogether with the driving tube when the driving tube is removed, withthe result that the cardboard wick can always be driven to uniformdepths.

Another embodiment of the invention is shown in FIG. 6. In thisembodiment, the upper construction of the mouth piece 7 is exactly thesame as that shown in FIG. 2, but a concave part 26 of trapezoid crosssection adapted to form a sand arch is provided on the lower surface ofthe mouth piece at the lower edge of the insertion bore 14. By thisconstruction, the driving tube is driven directly when there is a sandlayer on the upper part of the muddy soil. In cases where there is nosand layer, or a sand layer of unsuitable character, sand is placed onthe location where the operation is to be effected, and the driving tubeis then driven whereby a sand arch 27 is formed by the driving pressurein the concave part 26 so that it is possible to prevent theinfiltration of themuddy water into the bore 14. In some cases, it maybe necessary to add a slight amount of air pressure to the bore duringthe driving operation so as to increase the effect of preventinginfiltration of the muddy water.

Accordingly, the compressed air may be fed into the bore 14 only whenthe driving tube is removed to exhaust the air from the nozzle 14', withthe result that the sand arch 27 is blown away. Hence, the infiltrationof muddy water into the bore 14 is prevented and the quantity ofcompressed air needed is reduced.

In this case, when the compressed air is exhausted into the concave part26' through passage 28 as shown in FIG. 9, the sand arch 27 is blownoff, but the exhausted air causes the pressure in the lower part of themouth piece 7 to become higher, and the exhausted air will infiltrateinto insertion bore 29 together with the muddy water, whereby thecardboard wick driving efficiency is reduced due to the mud clogging thebore. Under these circumstances, the compressed air must always be fedinto the insertion bore 14.

While the above description relates to the apparatus for driving adriving tube into the thixotropic muddy soil, it will be obvious thatthe embodiments mentioned above are applicable to the case of driving adriving tube into soft sea-bottom sediments through the water.

Essentially, this invention makes it possible to drive a cardboard wickfor the cardboard-drain process into the thixotropic muddy soils, whichoperation heretofore has been considered to be impossible, and therebycontributes considerably to widening the scope of applications of thecardboard-drain process.

I claim:

1. An apparatus for driving a cardboard wick in the cardboard-drainprocess comprising a driving tube having therethrough a carboard wickinsertion bore through which a cardboard wick is inserted, pressurereducing members attached to the inner wall of said insertion bore andadapted to contact lightly said cardboard wick, said pressure reducingmembers thereby functioning to partition said cardboard wick insertionbore into an upper bore and a lower bore, the lower part of said lowerbore being formed as a nozzle by narrowing the space between said lowerbore wall and said cardboard wick, and means adapted to supplycompressed air into said lower bore during the driving operation,thereby to prevent infiltration of mud or water into said cardboard wickinsertion bore.

2. An apparatus for driving a cardboard wick in the cardboard-drainprocess comprising a driving tube having therethrough a cardboard wickinsertion bore through which a cardboard wick is inserted, said drivingtube having on its lower end surface and at the lower end of saidcardboard wick insertion bore a conical, outwardly diverging recess forforming a sand arch, said recess communicating at its inner end withsaid cardboard wick insertion bore, pressure reducing members attachedto the inner wall of said cardboard wick insertion bore and adapted tocontact lightly said cardboard wick, said pressure reducing membersthereby functioning to partition said cardboard wick insertion bore intoan upper bore and a lower bore, the lower part of said lower bore beingformed as a nozzle by narrowing the space between said lower bore walland said cardboard wick, and means to supply compressed air into saidlower bore at the time of the driving tube withdrawal step in thedriving operation, thereby to prevent infiltration of mud or water intosaid cardboard wick insertion bore.

References Cited by the Examiner UNITED STATES PATENTS 2,482,673 9/1949Kjellrnan 61-11 2,577,252 12/1951 Kjellman 61-11 OTHER REFERENCES Roadsand Streets, September 1955, p. 99.

EARL J. WITMER, Primary Examiner.

1. AN APPARATUS FOR DRIVING A CARDBOARD WICK IN THE CARDBOARD-DRAINPROCESS COMPRISING A DRIVING TUBE HAVING THERETHROUGH A CARDBOARD WICKINSERTION BORE THROUGH WHICH A CARDBOARD WICK IS INSERTED, PRESSUREREDUCING MEMBERS ATTACHED TO THE INNER WALL OF SAID INSERTION BORE ANDADAPTED TO CONTACT LIGHTLY SAID CARDBOARD WICK, SAID PRESSURE REDUCINGMEMBERS THEREBY FUNCTIONING TO PARTITION SAID CARDBOARD WICK INSERTIONBORE INTO AN UPPER BORE AND A LOWER BORE, THE LOWER PART OF SAID LOWERBORE BEING FORMED AS A NOZZLE BY NARROWING THE SPACE BETWEEN SAID LOWERBORE WALL AND SAID CARDBOARD WICK, AND MEANS ADAPTED TO SUPPLYCOMPRESSED AIR INTO SAID LOWER BORE DURING THE DRIVING OPERATION,THEREBY TO PREVENT INFILTRATION OF MUD OR WATER INTO SAID CARDBOARD WICKINSERTION BORE.